Multistage pump and pumping system



July 23, 1935. A. c. KLECKNER MULTISTAGE PUMP AND PUMPING SYSTEM Filed April 12, 1952 3 Sheets-Sheet 1 J0 036 Jj vflrfiiar CfKieC/zzer July 23, 1935. A KLE KNER 2,009,131

MULTISTAGE PUMP AND PUMPING SYSTEM Filed April 12, 1952 3 Sheets-Sheet 2 fig July 23, 1935. A. c. KLECKNER MULTISTAGE PUMP AND PUMPING SYSTEM Filed April 12, 1932 3 Sheets-Sheet I5 Patented Jul 23, 1935 2,009,137

UNITED STATES PATENT OFFICE MULTISTAGE PUMP AND PUMPING SYSTEM Arthur C. Kieckner, Racine, Wis., assignor to Webster Electric Company, Racine, Wis., a corporation of Wisconsin Application April 12, 1932, Serial No. 604,834

3 Claims. (Cl. 103-126) The present invention relates to multi-stage Another object of the Invention is the provipumps and-pumping systems particularly adaptsion of an improved rotary pump having very deed to be used in the fuel supply systems for oil sirable characteristics from the point 01' view of burners or the like, but the pump and system regulation so that the delivery requirements at 5 are of general application, and may be utilized the output and the suction conditions at the 5 wherever it is desired to supply liquid at a subinput do not materially affect the pressure stantially constant pressure under varying concharacteristics of the pump throughout the range ditions of delivery or supply. 0f the usual operating conditions.

One of the greatest difiiculties in the mainte- Another object of the invention is the provision nance of the fuel pumps of the prior art has been of an improved pumping system by means of 10 in the maintenance of a fluid-tight packing surwhich liquid may be supplied to the high pressure rounding the drive shaft. In order to make some side of a multi-stage pump at a substantially conpackings fluid-tight or nearly so, such great presstant volume and pressure so that the high pressure must be placed upon the packing that a sure side of the pump may operate under sublarge amount of power is consumed in driving stantially constant pressure coiidtions at its 15 the shaft about which the packifig is arranged. intake port and thereby eilect a better regulation Such heavy packing pressure is t e cause of exat the delivery end of the rotary pump. cessive wear on the packing and it is, therefore, Another object of the invention is the provision evident that the use of excessive pressure on the of an improved rotary pump which is so conpacking itself does not solve the problem and structed and arranged that the difiiculties caused 20 merely leads to greater difiiculties. by the necessity for using a packing about the The fuel pumps of the prior artt1 have also had drive shaft are substantially elimsnated and so a relatively poor regulation in t at the volume that any leakage which occurs along the drive and/or pressure of the liquid delivered from the shaft from the high pressure end of the pump is pump varied greatly with the amount of liquid collected and conveyed back into useful chan- 25 in the supply tank; that is, the pumps of the nels, and it is not absolutely necessary to enprior art delivered the liquid fuel in greater voldeavor to prevent leakage from the high presume when the tank was full than when the tank sure chamber. was empty, and the volume of liquid delivered by Another object of the invention is the provision 3 p p else Varied reatly with the resistance of an improved rotary pump having an improved interposed by the nozzle of the burner or other packing arrangement and low pressure supply apparatus. so that the packing is not subjected to high fluid When an excesslve nozzle esis ce 5 e pressures and it is not necessary to subject the countered i the use Of the pumps 0f the prior packing to excessive packing pressure to seal the art, there S a marked tendency on e a of shaft at the fluid pressures used, thereby main- 35 deliveryhfomme to The drop in volume taining an effective seal without the necessity for 'F 10h rfasults f lfaaks the tank excessive wear on the packing or the use of much line or in increase in suction resistance is another power for overcoming packing resistance sgz' g g g i g pr regu1at1n of the pumps of Another object of the invention is the provision 40 1 40 One of the objects of the present invention is g gi iz gg i gfig gfi g zz rjg s giif the provision of an improved liquid pump which i t d 1 d t d t f f is self-priming by virtue of its improved construcac ure an ap e opfer (mu 1 s i tion and mode of Operation so that the pump will tions for long periods of time without necessity immediately perform its functions on starting, for repau rfeplacement of Its parts Another obJect of the invention is the proeven though the tank and pipe lines had been I completely emptied during the last operation of V1510 of an lmpmvedmethod of Pmvidmg fuel supply for oil burners and the like and the prothe pump,

Another object of the invention is the proviof an improved System includmg an sion of an improved rotary pump which is adapt- Proved Pressure regulator- 50 ed to effect a delivery of fluid at substantially con- Other objects and advantages of the v i n stant volume and pressure throughout a con- Will be apparent from the following s p n siderable range of variation in the depth, presd t ac p y g aw s, in which sure or head of the fluid at the intake end of the similar characters of reference indicate similar 55 pump parw throughout the several views.

Referring to the drawings, of which there are three sheets,

Fig. 1 is a diagrammatic elevational view in partial section, showing a pumping system constructed according to the present invention;

Fig. 2 is a side elevational view of the pump unit;

Fig. 3 is a medial sectional view of the pump unit taken on a vertical plane, passing through the axis of the drive shaft, with the shafts in partial section;

Fig. 4 is a vertical elevational view in partial section, taken on the plane of the line 4-4 of Fig. 3, looking in the direction of the arrows, showing the mechanism in the high pressure side of the pump;

Fig. 5 is a similar view, in partial section, taken on the plane of the line 55 of Fig. 3, showing the arrangement of the low pressure side of the pump;

Fig. 6 isa plan view of the pump, with the pump in partial section on the plane of theline 66 of Fig. 3, looking in the direction of the arrows, showing the various conduits;

Fig. 'I is a diagrammatic view in perspective, showing the rotary pump gears and the course of the liquid during the operation of the pump;

Fig. 8 is a side elevational view of a combined pump and regulator unit constructed according to the present invention;

of the line 9-9 of Fig. 8 looking in the direction of the arrows;

Fig. 10 is a side elevational view of the combined pump and regulator unit taken from the right in Fig. 8;

Fig. 11 is a reproduction of the performance curves of the pump, showing the gallons per hour and pressure in pounds per square inch, to show the relation of volume and output pressure; and

Fig. 12 is a reproduction of the performance curves at fixed output pressure, showing the gallons per hour and suction in inches of vacuum, to show the relation of the suction resistance to volume output.

Referring to Figs. 2, 3 and 7, the pump unit, which is indicated in its entirety by the numeral I0, preferably includes a pump casing II, with.

a low pressure chamber l2 and a high pressure chamber I3, separated by a partition l4.

The mechanism of the pump preferably comprises a drive shaft IS, an appropriate electric motor or other source of power IS, a pair of high pressure gears l1, l8, and a pair of low pressure gears l9-20.

Referring to Fig. '7, it will be noted that the two gears l1 and are mounted on the drive shaft I5, while the gears l8 and is are mounted on the stub shaft 2|. It should also be noted that the projecting end 22 of the drive shaft I5 is located so as to project from the low pressure side of the pump so that the drive shaft need only be provided with packing adequate to take care of a relatively low pressure.

The course of the liquid through the pump is diagrammatically illustrated in Fig. '7 by the dotted line 23 and the arrows which show that the liquid passes into the chamber at the front of the gears i9 and 20 in Fig. 7. The clockwise rotation of the shaft 22 and gear 20 and the counterclockwise rotation of the shaft 2| and gear l9, as indicated, tends to produce a liquid pressure at the opposite side or the rear side of the gears I9 and 20 in Fig. '7.

The line 24 and its arrows indicate the overflow or output of excess liquid from the low pressure side of the pump, and the line 25 with its arrows describes the course of the liquid which is fed from the low pressure output to the high pressure input.

The line 26 and arrow drawn from the rear side of the gears l1 and 18 in Fig. 7 indicate the direction-of the high pressure output and the general location of the output conduit for the high pressure side of the pump.

It will thus be observed that liquid is pumped into the low pressure chamber by means of the mechanism on the low pressure side of the pump and transferred from the output of the low pressure side to the input of the high pressure side. The low pressure pumping mechanism supplies an excess of liquid for the input to the high pressure side of the pump, and the excess is permitted to flow back to the tank. The high pressure pump stage is thus provided with a supply of liquid at a substantially constant pressure, and the capacity of the low pressure stage may be made such that thereis always an excess of liquid to be returned to the tank, and consequently the pressure of the supply to the high pressure stage will not vary greatly.

Referring to Fig. 1, 21 is a diagrammatic illustration of a tank of any kind which is provided with a supply 28 of liquid fuel, such as oil, and

adapted to be pumped by the pump unit l0. Fig. 9 is a sectional view taken on the plane The intake conduit 29 from the intake 30 of the pump leads to the bottom of the tank or receptacle 21 so as to render practically all of theli'quid in the tank available for pumping, and an overflow conduit 3| leads from the low pressure outlet 32 of the pump 10 back to the tank.

The high pressure outlet 33 of the pump is connected with a pipe or conduit 34, which may be directly connected to the nozzle of the oil burner or other device which is to be supplied with liquid under pressure.

In the preferred embodiment of the invention, however, the system will be provided with a pressure regulator, indicated in its entirety by the numeral 35, and comprising a casing 36 having a liquid chamber 31. The conduit 34 communicates with the interior of the liquid chamber 31 at the inlet port 38.

The casing 36 may be formed with an outwardly projecting lug 39, formed with a threaded bore for receiving'the threaded end of a conduit 4| leading to the burner nozzle. At the inner end of the bore 40 it may be provided with a i'rustoconical seat 42 for seating the complementary end 43 of a needle valve 44. The needle valve may have its body 45 provided with a slot or aperture for receiving a transverse lever 46, which is pivoted by a pin 41. The upper end of the needle valve body may be secured by a rivet, bolt, or other convenient means to the closed end 48 of an expansible sheet metal bellows 49.

The bellows 49 is preferably provided with radially extending attaching flange 50 at its open end, and the flange 50 may be clamped between a cover 5| and an'attaching flange 52, by means of a multiplicity of screw bolts 53 which pass through the cover and are threaded into the flange 52.

The cover 5| is also preferably provided with a threaded bore 54 for receiving a screw bolt 55 having a lock nut 56. The inner end of the screw bolt 55 engages a spring plate 51 which is formed with an annular depression or groove 58 providing a seat for the helical compression spring 59. A similar spring plate provides a seat for the compression spring 59 at its opposite end and engages the closed end 48 of the bellows 49. The

spring 59 tends to maintain the needle valve 44 in closed position until a predetermined liquid pressure is built up in the regulator chamber 31 so as to compress the bellows 49. The interior of the bellows 49 communicates with the atmosphere through one or more air holes 6| in the cover 5|. The pressure at which the valve 44 will be actuated or opened may be regulated or predetermined by adjustment of the screw bolt 55 which is adapted to adjust the spring pressure inside the bellows 49.

The lever 46 is preferably provided with a twisted end 62, which may be pivoted in a groove 63 formed in one side of the casing 36. The opposite end of the lever 46 is pivoted to a piston valve 64 by means of a pin 65. The casing 36 is also preferably provided with a projecting lug 66, which may be provided with a threaded bore 61 for receiving the threaded end of the overflow conduit 68 leading from the pressure regulator back to the tank 21.

The bore 61' is adapted to slidably receive the cylindrical body of the piston valve 64 to effect a closure of the bore until the bellows 49 is compressed to a predetermined degree. The piston valve 64 is also provided with a tapered throttling surface 69 which effects a gradual opening of the piston valve when the piston 64 is raised a predetermined amount by the lever 46.

It will be observed that the piston valve is located at the end of lever 46, where it will have a much greater movement than the needle valve 44. and the contour of the surface 69 may be made such asto accomplish a very close regulation of the pressure in the regulator chamber 31, so that the nozzle 4! will be supplied with liquid at a substantially constant pressure.

The operation of the pressure regulator is as follows: When the pump it! is not operating, the pressure of the spring 59 closes the needle valve 44 and the piston valve 54. As soon as the pressure generated by the pump 10 builds up the pressure in the regulator chamber 31 to the proper amount the liquid pressure will cause the bellows 69 to collapse against the compression of spring 59 and needle valve M will beopened to supply liquid under pressure to the nozzle.

The pump it is adapted to supply more liquid under high pressure than is necessary for the ordinary operation of the nozzle or other device in order to assure the maintenance of the proper pressure at the nozzle, but as soon as the pressure builds up above a predetermined amount, the bellows '39 will collapse still further, and the piston valve 66 will be opened to permit the excess liquid to flow back to the tank through the conduit 68.

The multiplying mechanism which actuates the piston valve 64 makes the piston valve quite sensitive and decreases the range of pressure variation of the device.

It should be understood, however, that the pressure regulator 35 need only be used in the system whenever extremely close regulation of pressure is required, and in some embodiments of the inventionthe pump unit in is adapted to provide a supply of liquid under sufficiently constant pressure so that no pressure regulator need be employed.

Referring to Fig. 3, the casing H of the pump unit is preferably formed of a substantially oblong metal member 10 having an oblong chamber 1| and having both of its ends open. The ends of the casing are closed by cover plate 12' and cover plate 13'.

In order to provide an eflicient rotary pump,

the parts of the casing and pump mechanism must be very accurately machined, and'should preferably be constructed of the best steel or any suitable steel alloy suitable for. accurate machining and long wear.

Referring to Fig. 3, it will be observed that the oblong chamber H is adapted to receive the gears l1 to 20. The gears |120 may be provided with a multiplicity of teeth 1215, which are preferably of the same number and shapeon each gear. The side surfaces of the teeth 12- may be formed according to the best practice for providing a rolling contact between the adjacent surfaces and for eliminating noise and leakage between the teeth at the center of the pump. The periphery of each of the gears l120 or the outside edges of the teeth are provided with curved surfaces 16, forming portions of a cylinder, the

surfaces being substantially complementary to the cylindrically curved walls 11, 18 located within oblong chambers 1| at each end. The side walls 19 and of the oblong chamber 1| are preferably substantially plane and located tangent to the semi-circular or cylindrical walls 11, 18 at each end.

In order to form the low pressure chamber l2 and the high pressure chamber I3 in the oblong chamber II, the casing is provided with partition l4. It would be extremely difficult, if not impossible, to form the corners 8| at the inner ends of the chambers I2 and I3 with a sharp right angle on account of the tendency for tools to become dull at the point or apex of two blades which are disposed at an angle to each other. This would be the cause of an inaccurate fit between the end surfaces of the gears and the partition i4 and therefore I prefer to form the partition M of a separate piece of metal which has an external surface substantially complementary to the surface of the oblong chamber 11. The partition i4 may then be provided with its transverse conduit 82 without any difficulty before the partition is put in place, and also with the bleeder conduits 83, the purposes of which will be described in detail hereinafter.

The partition i4 is made sufiiciently large and fits the oblong chamber 11 in such a manner that there is a close frictional engagement between the external surface of the partition l4 and the internal walls of the chamber 11. The parts may be heated, prior to their assembly by means of a press and the casing 10 may be permitted to contract about the partition M to secure it in place.

It will be noted that the partition M is so located that the high pressure chamber i3 is relatively small, while the low pressure chamber i2is relatively large. The low pressure chamber i2 is made larger in order to accommodate larger gears and to provide an-excess supply of liquid under low pressure for the intake side of the high pressure stage.

Each end of the partition M is machined to a substantially plane surface 85 and the adjacent ends of the gears are also machined to a substantially plane surface to engage the surface of the partition. The thickness of the gears is such that the outer end surfaces of the gears, which are also machined to a substantially plane surface, are flush with the'fiat end surfaces 86 of the casing, and when the cover plates 12 and 13 are secured on the casing ,the inner surfaces 81 of the cover plates are in close sliding engagement with the ends of the gears.

In other words, the gears l120 fit accuratelyin the gear chambers l2, I3, and the peripheral surfaces I6 of the gears are in sliding engagement with the curved walls 18.

The partition I4 is preferably provided with a pair of substantially cylindrical bores 88-48 adapted to receive the complementary cylindrical portions 90, 0| of the shafts'IB and 2|. The shaft 2| is provided with a reduced cylindrical portion 82 which is adapted to be received in the cornplementary cylindrical bore 83 in gear I8. A transverse slot 84 is formed in the end of shaft 2| and extends into the side walls of the bore 88 in gear I8. A transverse pin 00 is located in the slots 94, 88, and the. pin causes the gear I8 to be driven by shaft 8|.

In a similar manner gear I8 is rotatably mounted on the reduced cylindrical end 01 at the right end of stud shaft 2| and the gear I0 is keyed to shaft 2| by a pin 98.

In order to facilitate the accurate machining of the cylindrical surfaces 82, 9| and 81 on the shaft 2|, the shaft is formed with grooves 99, I00 between these cylindrical surfaces respectively so that the tools in grinding one surface may not overlap on the adjacent surface which is of a different diameter. The same is true of the left .end of shaft I5 which is formed with cylindrical surfaces 90, |0I and I02 separated by grooves I03, I04. The cylindrical surface |0I is rotatably recelved in the bore I05 in gear I1, and cylindrical surface I02 is received in a complementary bore in gear 20. Since gear 20 drives all of the other gears in the embodiment illustrated, it is provided with longitudinally extending slots I06 for receiving a pair of pins I0'I which are located in transverse bores I08 in the drive shaft I5.

In some embodiments of the invention the gears may be splined to the shafts in many other different ways, but it is found that when the gears are arranged as a train so that they are driven one by the other from one end of the train to the other, all of the backlash is taken up when the gears are being driven and there is no possibility of noise due to backlash. The splining of the gears, as shown in Fig. 3, is found to reduce the amount of noise caused by the gears quite materially.

The cover plates I2, I3 may be secured to the casing I0 by means of a plurality of screw bolts I09 which pass through apertures in the cover 12' and through registering bores in the casing 10, and are threaded into threaded bores in the end plate I3. The oblong casing II is preferably formed with integral projections IIO, III, II2, provided with threaded bores 33, 32 and 30 respectively, which form the inlet and outlet ports and are adapted to receive the threaded ends of the pipes 34, 3| and 29 respectively.

, Referring to Fig. 5, the inlet port or bore 30 communicates with a conduit II3 which leads to an inlet port .4 located at the low pressure end of the pump in chamber I2 on the side toward which the gears I9 and 20 are rotating. The overflow outlet port 32 communicates through a conduit 5 with an overflow port- IIG which is located in the opposite wall of the low pressure chamber I2 on the side from-which the gears rotate, withreference to the interengaging parts of the gears.

The counterclockwise rotation of the gear I0 and clockwise rotation of the gear 20 in Fig. 5

tends to carry liquid from the point II'I about the outer periphery of the gears adjacent the curved walls "and 78 and creates a pressure at the point II8 at the right hand side of the chamber I2 mm. 5.

The space in chamber I2 at the point III thus constitutes a source of liquid under reduced pressure for supply to the high pressure stage of the pump, and the excess liquid is carried off by the conduits I I5, 82, 3| back to the tank. The liquid under reduced pressure is supplied to the high pressurechamber I3 through the diagonal conduit 82 (Fig. 6) which is so located as to form a port II9 adjacent the overflow port III.

When the pump is operating, liquid flows in the direction of the arrow shown in Fig. 6 through the diagonal conduit 82 and the opposite end I28 of the conduit 82 forms an inlet port for a high pressure chamber at the right side of Fig. 4.

Since Fig. 4 is a view looking at the other end of the pump, the gear II will rotate in a clockwise direction and the gear I8 will rotate in a counterclockwise direction.

The operation of the gears IT and I8 in their high pressure chamber I3 is substantially the same as described with respect, to the low pressure side.

The liquid is engaged by the teeth as it issues from the intake port I20 and is entrained by the teeth about the periphery and carried along the periphery of the gears and along the curved walls I1, I8 to the space |2I at the left side of the high pressure chamber I3 in Fig. 4, tending to cause a high pressure in the liquid within the space I2I. The space |2I communicates with the outlet port 33 through the conduit I22 and port 33 is the high pressure outlet of the pump.

On account of the formation of the teeth I4 there is some tendency toward-the squeezing or compression of the liquid at the points between the gears as thetooth rolls or slides down into the space between two adjacent teeth. This compression between the teeth results in a slight noise and should preferably be relieved in such manner as will not affect the efficiency of the teeth in their pumping action when they are in engagement with the curved walls I1, I8.

In order to relieve this pressure between the engaging teeth, the partition I4 is preferably provided with a plurality of bleeder conduits 83, which are located to permit the liquid under pres sure from the high pressure side to flow out sidewise from between the teeth as they come into engagement with each other. One of the conduits 83 is located in Fig. 4 to register with the base of the groove between the teeth of gear I1, and the other conduit-83 is located to registerwith the base of the grooves between the teeth of the gearI8.

This effect is present to some extent in both the high pressure and low pressure chambers, but it is found that the noise and resistance to rotation which is caused by this effect are relieved by permitting the liquid between the high pressure teeth to flow back to the low pressure side. I I; I1]

The end plate I3 is provided with an accurately machined circular bore I23 whichl ls adapted to rotatably receive the projectirfg end 22 of shaft IS. The end plate I3 is also preferably provided with a tubular formation I24 surrounding shaft I5 and formed with a counterbore I25. The base of counterbore I25 is provided with an expansion ring I26 which may consist of an annular sheet metal member of s ibstantially V shape in cross section and a plurality of packings I21 are compressed between expansion ring I26 and a similar expansion ring I28.

The tubular formation I24 is provided with a gland having an attaching flange I30 and havthe units are separate.

ing a cylindrical formation I 3i adapted to be received in counterbore I25. The gland may be secured to the member I24 by a plurality of screw bolts I32 passing through the attaching flange I36 and threaded into the member lid. The gland I29 is provided with a bearing I 33 formed of suitable bearing metal and located in a bore I66 and a helical packing spring its is compressed between the end of the gland i29 and expansion ring I28. The packing is thus automatically taken up as fast as it wears, and is maintained under a relatively low pressure by means of the compression spring I35.

Since the projecting end 22 of the drive shaft I5 leads into the low pressure chamber, it is not necessary to pack the drive shaft 22 so securely as would be necessary if a high pressure were generated in chamber I2. As a matter of fact, the packing chamber I36 may actually be at a pressure which is slightly sub-atmospheric so that any leakage past the packing I271 may be drawn back into the low pressure chamber I2.

For this purpose the plate I3 may be formed with an aperture I 37 leading from the packing chamber 35 to the intake side II? of the low pressure chamber.

It might be supposed that since the gears I'I-2Il are all driven from the'sanie shaft at the same speed the pressures generated by the two stages of the pump might be substantially the same or that the pressure generated by the larger gears might be greater than that generated by the smaller gears. These pressures, however, depend not only upon the rate of rotation of the gears, but upon the relative sizes of the supply and outlet ports, and particularly upon the resistance to discharge from the pump which is encountered at the. outlet side of the pump. The pressure builds up as the outlet resistance is increased. The pressure on the low pressure side is extremely low or sub-atmospheric because of the free return of liquid to the tank from that side. The sizes of the gears I 9 and 26 on the low pressure side are such that the low pressure stage is adapted to pump or to suck about fifty gallons of liquid per hour and supply it to the high pressure side at a pressure which may be slightly sub-atmospheric or slightly above atmospheric.

Referring to Figs. 8, 9 and 10, these are views of a combined pump and regulator unit, which has great advantages over the devices of the prior art and the separate pump and regulator units by reason of a saving in cost of material and labor in the installation.

The combined unit is more easy to install because there is no necessity for a number of different pipes which are otherwise required where The combined pump and regulator unit is indicated in its entirety by the numeral I40, and it preferably consists of a pump indicated by the numeral I6 and a regulator MI. The pump It) may be substantially similar in construction to that previously described except that it is not provided with the customary pipe fittings III], III and H2 for attachment of the pipes, but the conduits leading from the pump all extend to the upper flat surface I42 of the pump casing. 'The pump casing is provided with attaching flanges I43 having apertures I44 for receiving the screw bolts I45 which" are threaded into the body of the regulator casing I46 to" secure the parts of the unit together. The base of the regulator casing I46 is likewise provided with a flat surface I41 or a surface complementary to the surface M2 on the pump casing, and

the conduits of the regulator casing I66, which stantially cylindrical chamber I49 for housing the pressure bellows I56. The bellows I56 is provided with an outwardly extending flange which is clamped between the cover 56 and the casing I46 by means of screw bolts 53, and the cover is provided with an adjustment screw bolt 55 for adjusting the pressure on the spring, as shown in detail in Fig. l.

The closed end of the bellows I 56 supports a piston valve i5i for controlling an overflow port.

I52, and the piston valve may support a needle valve I53 for controlling an output port I56. The needle valve I53 is preferably provided with a frusto-conical end surface I55 for engaging a complementary seat. The length of the piston valve Isl is such that it does not uncover the overflow port I52, until the needle valve I53 is already opened, and the pressure on the bellows I56 has been increased to an amount more than that required for the burner.

The regulator of Figs. 8 to 10 is thus adapted to operate substantially the same as the regulator previously'described, but the extremely flex-- ible bellows I56 gives the device a range of movement which permits it to control two valves i5i, I53 successively by movement in the same direction.

It is not necessary, therefore, to describe in detail all of the parts of the pump and regulator, but the course of the liquid through'the pump and regulator will be described in order to show the connection between the various conduits and the elimination of pipes which have been rendered unnecessary by the use of a combined unit.

Referring to Fig. 9, the regulator casing M6 is provided with a threaded bore I56 which forms the inlet for the pipe from the tank and corresponds to the inlet 30 of Fig. 1 connected with, pipe 29. A conduit I51 leads from the inner endof the bore I56 downward to a counterbore I58, which registers with a counterbore I56 formed in the surface I42 of the pump. The counterbore I59 communicates with a bore or conduit H3 leading to the port II4 at the input of the low pressure side of the pump. A diagonally extending conduit 32 (Fig. 10) conducts liquid .from the output of the low pressure side to the input of the high pressure side, and is omitted in Fig. 8 for the purpose of clarity. The outlet I20 of this diagonal conduit is indicated in Figs. 8 and 10.

Referring to Fig. 9, a conduit II5 leads upward from the low pressure output and communicates with the threaded bore I66, which is adapted to receive a single overflow pipe leading back to the tank. A conduit I22 leads from the output of the high pressureside of the pump and communicates with a counterbore I6I in the surface I42. Counterbore I5I registers withthe counterbore I62 in the surface I41 of the regulator casing I46, and the regulator casing is provided with a conduit I64, communicating with counterbore I62. Conduit I64 conducts fluid from the high pressure side of the pump to the pressure chamber 31 of the regulator unit. The liquid under pressure first forces the bellows I50, piston valve I5I and needle valve I53 upward to open the port I54. Port I54 communicates with a'downwardly extending conduit I65 which communicates with a laterally extending conduit I66. The laterally extending conduit I66 (Fig. 9) communicates with a threaded bore I61, which is adapted to receive a pipe leading to the burner.

The piston valve is slidably mounted in a bore I68 to control the flow of liquid through the overflow port I52. The conduit I64, which leads liquid under high pressure to the pressure chamber 31, also communicates through a conduit I69 with the cylindrical chamber I49 in which the bellows I50 is located. The bellows I50 is thus always sub- Jected to the same pressure that exists in the pressure chamber 31, andthe chamber I49 may be considered a part of the pressure chamber 31 for certain purposes.

When the pressure'in the pressure chamber 31 rises above a predetermined value, the upward movement of the piston valve I5I with the bellows I50 causes the piston valve I5I to uncover port I52, which is the overflow port. Port I52 communicates by conduit I10 with the bore I60. The conduit I63, which is observed in Fig. 8, does not communicate with the counterbore I62, but with a counterbore l1I disposed on the other side of the unit. Conduit I63 thus communicates with the low pressure output conduit I I5 from the low pressure side of the pump and is adapted to carry back to the tankthe excess liquid from the low pressure side of the pump. Conduit I10 conveys back to the tank through the bore I60 and an appropriate pipe the excess liquid from the pressure chamber 31 of the regulator.

' It will thus be observed that a single overflow conduit may be used to carry back excess liquid from the regulator unit and from the low pressure stage of the pump when the combined unit is used. Furthermore, there is no necessity for the interconnecting pipe 34 of Fig. 1, when the combined unit is used; and there will be one outlet to the burner, one input pipe from the tank, and one return pipe to the tank when the combined regulator and pump unit of Flgs.6 to 10 is employed.

The sizes of the gears I0 and 20 relative to the gears on the high pressure side may be varied considerably, but the low pressure stage should preferably pump an excess of liquid over that' necessary for the high pressure stage. Thus the low pressure stage may be adapted to suck up about fifty gallons of liquid per hour, and to supply liquid to the high pressure side at a pressure which may be slightly sub-atmospheric or slightly above atmospheric.

The intake pressure for the high pressure side may even be sub-atmospheric it the tank is located below the pump, so that there would be no tendency-for leakage through the packing. In the ordinary installation the output pressure or the low pressure stage would be slightly above atmospheric on account of the return resistance of the overflow pipe 3i, but the input pressure at the intake of the low pressure side wouldbe subatmospherlc so that any leakage past a packing I21 will be sucked back into the low pressure stage through the conduit I31 (Fig. 6), and the packing need not be subjected to any severe conditions of service. About fifteen gallons per hour, for example, oi the liquid supplied by the low pressure stage may be taken into the high presure stage and delivered through the high pressure outlet 33, while the balance oi thirty-five gallons may be returned to the tank through the overflow conduit 3|.

The characteristics 0! a pump or this type should be noted in the case of the pump per se and in connection with an oil burner system, as all 01 the advantages may not be evident from the performance in an oil burner system.

The present pump, has improved characteristics, from the point of view of regulation, over the devices of the prior art, and these characteristics are illustrated by the curves shown in Figs. 11 and 12.

In Fig. 11, the ordinates are provided with indicia indicating the gallons per hour, and the base line has indicia indicating the-pressure in pounds per square inch. In the test upon which these curves were based, the head of liquid in the tank was kept substantially constant and, as indicated at the top of the figure, the suction was fifteen inches of mercury.

The output pressure of the pump was regulated by increasing the spring pressure on the regulating valve on the output side and was varied from zero to three hundred pounds per square inch in determining the curve A. The volume of output remained substantially constant atabout thirty-four gallons per hour, thus demonstrating that at constant suction the pump was capable of delivering a constant volume through a variation of pressure from zero to three hundred pounds per square inch.

In the same test, the by-pass delivery was measured, the results being indicated by curve B, and it will be noted that the suction being constant, while the output pressure of the high pressure side was varied from zero tothree hundred pounds per square inch, the by-pass delivery changed very slowly from twenty-two gallons per hour to twenty-five gallons per hour. The slight upward slope of the by-p -f delivery curve B shows a very slight variation in bYrPfldelivery.

The curve C,- which is based upon the same test, indicates the results of measurement of the pressure delivery from the high pressure side of the pump, which varied only slightly, from twelve gallons per hour to nine gallons per hour.

The slight downward slope of the pressure delivery curve shows that the volume output on the high pressure side or the pump varied only slight ly during an extremely large variation which was made in the pressure of the output.

The curve A represents the sum of the by-pass delivery B and the pressure delivery C, since the total volume is the sum of the by-pass delivery volume and the pressure delivery volume.

These curves demonstrate conclusively that the volume output does not fall of! materially, although the pressure may be raised considerably by the resistance encountered at the output side. The pump will continue to deliver its rated volume, or substantially that volume, irrespective of the resistance encountered at the output side.

Referring to Fig. 12, these curves D, E and F show the results attained in a test at constant output pressure of one hundred pounds per square inch at the high pressure side. The gallons per hour output are plotted against the suction in inches of vacuum. In this case a throttle was applied to the conduit at the suction side or the pump, and the result of increased resistance at the suction side of the pump on delivery in gallons per hour was determined. The curve E shows the gallons per hour delivered at the by- W 15$ the $l1t10n was increased. of course, the

by-pass delivery volume is important only for the purpose of providing an excess supply of liquid to maintain the characteristics of the high pressure side of the pump by providing a constant supply of liquid at the input of the high pressure stage. As the suction was increased by-pass delivery, starting at twenty-six gallons per hour, dropped ofi rather slowly until about fifteen inches of suction when the by-pass delivery dropped off quickly and the curve strikes the axis at about 27 inches of vacuum in the pump tested; that is, at the ordinate 2? the resistance at the input side of the pump had so affected the pump that of the liquid which was sucked up by the pump was being put out at the high pressure side of the pump and there was no excess left to be I returned to the tank through the by-pass delivery side by the low pressure side.

The curve represents the sum of the ordinates of curves E and F and is the total output curve under the same conditions. At the point G in the curves D and F, the suction resistance was so great that sufiicient liquid was not supplied to the high pressure stage by the low pressure stage to maintain the volume, and consequently the volume dropped oil.

The important conclusion to be drawn from the curves of Fig. 12 is that throughout a very wide variation in suction at the input side, with a constant output of pressure of one hundred pounds per square inch, the volume output at the high pressure side to the burner remains substantially constant.

It should be remembered that these tests were carried on without the use of any regulator valve or NH except as a means to throttle the output passage to increase output resistance and raise the pressure and the curves show the characteristics of the pump per se under the conditions described. For certain types of installations it may be entirely unnecessary to utilize any regulator valve when a pump constructed according to the present invention is employed, but the regulator valve is adapted to insure even a more close regulation of the conditions under which liquid is supplied to the burner. I

A regulator valve is generally necessary in any ordinary oil burner installation as a safety device to prevent pressure building up in the lines beyond a predetermined limit and to prevent bursting of the conduits because the output resistance interposed by a nozzle usually varies somewhat, due to the dirt and other foreign matter in the oil, which tends to clog the nozzle at least momentarily, causing fluctuations in the resistance, resulting in fluctuations in output pressure.- The present pumping system is, however, adapted to deliver a constant volume of oil with or without a regulating valve.

The operation of the present invention will be apparent from the description of the various parts and the functions of each part. When the pump I0 is driven by the motor I5, liquid is pumped up or sucked up from the supply 28 in tank 21 by the low pressure stage of the pump and an excess supply is constantly provided at a predetermined pressure for the high pressure stage of the pump. The excess is such that although the head of the liquid in the tank 2'? may vary considerably from a full tank to an empty or almost empty tank, the high pressure stage is still supplied with the full amount of liquid at its'inlet necessary to assure its operation under substantially the same conditions. The pump is thus capable of supplying liquid fuel under pressure at a substantially constant pressure, irrespective of the head of liquid in the tank, and the present pump has highly improved characteristics with respcct to regulation over the pumps of the prior art.

In the case of an oil burner system, it should be noted that the pump and regulator valve (if one is employed) will be adjusted when the conditions are ideal, at the installation of the system. At that time, if the system is properly installed, the oil strainers should be clean and interpose but little resistance in the suction line. There should be no leaks in the suction line, and the only variation'to be expected under ideal conditions is the variation in the head of the liquid in the tank. However, as the use of the oil burner system goes on, the strainers become clogged and leaks often develop in the suction line, thedeaks sometimes being under ground where they cannot be found or corrected. The characteristics of the burner nozzle may also change due to clogging or burning. The present pump and pumping system is adapted to make the oil burner system operate satisfactorily, even under the most adverse conditions, and the pump has often been installed andthe burner found to operate satisfactorily under conditions where there were under-ground leaks or other troubles which would prevent the pumps of the prior art from operating satisfactorily.

Another advantage of the present invention lies in the fact that the manufacturer of the pump and regulator equipment may eifect a material saving in the cost of equipment by working closer to the volume requirements of any particular burner or other consuming apparatus. For instance, if'the consumption requirement is ten gallons per hour, an ample factor of safety would be provided in the present system by a pump adapted to supply the specific volume requirement or a little more than the volume requirement on account of the constant delivery characteristics of the pump, while other pumps would require the supply of a pump capable of delivering two or three times the volume require- ,ment in gallons per hour.

The present pumping system is self-priming by virtue of the improved arrangement of the parts of the pump in two stages. There is practically no resistance at the output side of the low pressure stage by reason of the use of the disposed at such a point that liquid is forced' to the pump by the externalpressure of air on the liquid in the tank when a partial vacuum is produced in the input side of the low pressure stage; that is, the output pressure of the low pressure stage may be sub-atmospheric. The

put over a permissible low pressure stage is self-priming and adapted to provide a supply of liquid for the high pressure stage so that the high pressure stage is also made self -priming.

There is always a film of oil remaining upon the walls of the gear chambers in the pump and upon the gears, even though the pump be prac-' tically empty, and this film of.oil is suflicient to insure the operation of the pump to produce a suction at the intake. Pumps of this type have been wiped entirely dry with a cloth and then located high above the tank, and upon starting of the pump it was found to be self-priming, even under those conditions.

The pump is preferably arranged with its conduits extending upward above the pumping chambers so that at least the low pressure will always be full or partially full of liquid and adapted -to supply liquid to the high pressure stage as soon as the pump is started, whether the pipes have been emptied or not. Thus the pump is self-priming, and this is a very important advantage in connection with oil burners because a great deal of trouble is caused when it is necessary to remove the pipes from a pump to prime the pump after the pipes and pump have become emptied, as experienced with the pumps of the prior art.

The present pumping system includes an improved pressure regulator which is more sensitive than the devices of the prior art, and the preferred form of pumping system includes overflows both from the multi-stage pump and from the regulator so that the pressure at the nozzle may be maintained more nearly constant than any of the devices of the prior art.

The only packing which is needed on the pump is used upon the low pressure side of the pump, andthis packing need not be subjected to excessive packing pressures because the fluid pressures under operating conditions at this point are not such as to require a very tight packing. Thus one of the greatest ditllculties encountered in rotary pumps of the prior art is eliminated by the ar rangement of the parts and packing of pumps constructed according to the present invention, and the packing may be expected to perform its functions for along period of time without necessity for renewal or other attention.

The present pump is less noisy than ordinary gear pumps of the prior art, and the pump is regulation of pressure by means of the tandem arrangement of its regulating devices. For instance, both the pump it and the regulator 35 have overflow or return conduits so that an excess of liquid is supplied to both of these devices, thereby maintaining constant pressure conditions at the input side of both the high pressure stage and the regulator so far asit is possible.

Suppose, for example, the pump is capable of effecting a regulation of the pressure at its outgiven range which does not exceed a variation. The variation which will occur in the supply to the therefore, be much less than that which would pressure regulator will,

occur if any other pumping device were used. The regulator will thus be able to provide a more nearly constant pressure output and the variation in pressure at the output of the regulator will be a fraction of the variation which might be expected if only one of these devices were used.

The tandem arrangement of the self-regu ating pump and the pressure regulator thus greatly increases the accuracy of maintenance of a constant pressure at the output of theregulator.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims. Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United States, is:

1. In a combined pressure generating and regulating unit for oil burners, the combination of a casing formed with a low pressure supply stage chamber and a high pressure pumping chamcess ofliquid over that required for the high pressure stage, a conduit extending from the low pressure output to the high pressure intake, said. unit having an intake conduit leading to the low pressure chamber, a burner outlet conduit connected with the high pressure outlet, and a bypass outlet, said by-pass outlet communicating with the output side of the low pressure stage and with a fuel supply tank, said unit having a pressure chamber in communication with the burner outlet conduit and a pressure responsive member in said chamber, a valve member operated by said pressure responsive member adapted to control the burner outlet port and to open the burner outlet port first, said valve member also controlling a conduit from said pressure chamber leading to the by-pass outlet whereby the excess of liquid'from said pressure chamber and from said low pressure stage are conveyed back from said by-pass outlet to the supply tank.

. 2. In a combined pressure generating and regsaid low pressure chamber having a capacity several times as great as that of the high pressure chamber, pumping gears in said low pressure and high pressure chambers of suitable size whereby the low pressure pump is adapted to pump an excess 'of liquid over that required for the high pressure stage, a conduit extending from the low pressure output to the high pressure intake, said unit having an intake conduit leading to the low pressure chamber, a burner outlet conduit connected with the high pressure outlet, and aby-pass outlet, said by-pass outlet communicating with the output side of the low pressure stage and with a fuel tank, said unit having a pressure chamber in communication with the burner outlet conduit and a pressure responsive member in said chamber, a valve member operated by said pressure responsive member adapted to control the burner outlet port and to open the burner outlet port first, said valve member also controlling a conduit from, said pressure chamber leading to the by-pass outlet whereby the excess of liquid from said pressure chamber and from said lowv pressure stage are conveyed back from said by-pass outlet to the supply tank, said valve member comprising a piston valve for controlling the by-pass outlet and a needle valve for controlling the burner outlet, said needle valve being opened first in point of time over said piston valve.

3. In a combined pressure generating and regulating unit for oil burners, the combination of a casing formed with a low pressure supply stage chamber and a high pressure pumping chamber, said low pressure chamber having a capacity several times as great as that of the high pressure chamber, pumping gears in said low pressure and high pressure chambers of suitable size whereby the low pressure pump is adapted to pump an excess of liquid over that required for the high pressure stage, a conduit extending from the low pressure output to the high pressure intake, said unit having an intake conduit leading to the low pressure chamber, a burner outlet conduit connected with the high pressure outlet, and a bypass outlet, said by-pass outlet communicating with the output side of the low pressure stage and with a fuel tank, said unit having a pressure chamber in communication with the burner outlet conduit and a pressure responsive member in said chamber, a valve member operated by said pressure responsive member'adapted to control the burner outlet port and to open the burner outlet port first, said valve member also controlling a 10 cluding a pump casing and a valve casing, said pump and valve casing being provided with registering conduits forming a unitary whole for generating and supplying liquid fuel at constant volumn irrespective of the output pressure and in- 20 take resistance.

, ARTHUR C. KLECKNER. 

